This will constitute continuation of our studies in the mechanism of oxidative phosphorylation in bacterial systems. The physicochemical properties of the isolated purified coupling factors and their interaction with adenine nucleotides will be analyzed. The interaction of the heat labile coupling factor (HLF) with modified adenine nucleotides will be studied in an effort to make covalent complexes between the nucleotides and the polypeptide subunits of HLF. Also, heavy metal derivatives of adenine nucleotides will be complexed to HLF and examined in the electron microscope in order to determine the three-dimensional structure of this enzyme. The long-range goal of this project is the elucidation of the mechanism of ATP synthesis. BIBLIOGRAPHIC REFERENCES: Adolfsen, R. and Moudrianakis, E. N. 1976. Binding of Adenine Nucleotides to the Purified 13S Coupling Factor of Bacterial Oxidative Phosphorylation. Arch. Biochem. Biophys. January. Moudrianakis, E. N. and Adolfsen, R. 1975. Polymorphism of Coupling Factors of Oxidative and Photosynthetic phosphorylation. In Electron-Transfer Chains and Oxidative Phosphorylation, ed E. Quagliariello et al., North Holland Publishing Co., Amsterdam.